The present invention relates to monitoring systems for power transmission chains of the kind that are used in drive systems including those for lifting and conveying applications. Such chains generally comprise a plurality of link plates interconnected by transverse pins.
Chains of the kind referred to above are typically used to transfer power and/or forces and can often be subjected to fluctuating loads. When problems arise in the operation of the chain drive, it is often difficult to diagnose precisely what is causing the disruption or ultimately the failure of the drive. Clear and easy access to all parts of the drive may not be possible and this creates problems. In order to assist in the diagnosis it is known to use data logging and transfer devices. An example in relation to the load upon a fork-lift truck lifting chain is described in European Patent Application No. 1 362 003. This describes the mounting of a sensor and data-logging unit onto the surface of a link plate of a lift chain. The unit has strain gauges, associated electrical circuitry, memory, and a transceiver. The strain gauges and associated signal processing circuitry provide an output signal that is indicative of the load applied to the chain at any point in time. This data may be stored, processed, and analyzed in the unit before being transmitted by a transceiver for onward transmission to a computer. Alternatively, the data may be transmitted directly to the computer without processing or analysis. Once the data is available it can be processed and analyzed to assess the chain condition and to determine whether the chain needs servicing or replacing.